Update issue templates

Adding bug report, documentation, and general inquiry templates. 

There's no easy way to redirect "general inquiry" directly to forum. If better option is available later, will update.

.github/ISSUE_TEMPLATE/bug-report.md

@@ -0,0 +1,36 @@
+---
+name: Bug report
+about: Create a report to help us improve our code.
+title: "[BUG]"
+labels: bug
+assignees: ''
+
+---
+
+**Describe the bug**
+A concise description of what the bug is.
+
+**Target**
+- Development board: [e.g. HiFive11 RevB]
+- Instruction Set Architecture: [e.g. RV32IMAC]
+- IDE and version: [e.g. Freedom Studio 4.12.0.2019-08-2]
+- Toolchain and version: [e.g. riscv64-unknown-elf-gcc-8.3.0-2019.08.0]
+
+**Host**
+- Host OS: [e.g. MacOS]
+- Version: [e.g. Mojave 10.14.6]
+
+**To Reproduce**
+- Use project ... and configure with ...
+- Run on ... and could observe ... 
+
+**Expected behavior**
+A concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Additional context**
+Add any other context about the problem here.
+e.g. code snippet to reproduce the issue.
+e.g. stack trace, memory dump, debugger log, and many etc.